Lock local controls and screen of remote pc

we have several radmin installation on our site to allow our users to work on the machines from home, other buildings etc.
Our security manager is giving us a hard time because industrial spies can see all our work without being noticed by the user. Or he can even take control of the machine and change settings when noticing that te remote user is not using it for a while. We therefor would like the possibility to "lock" the remote machine while being worked on via RADMIN. Like you can do while using remote dekstop.